<template>
<div class="box">子组件

 <div>
     {{ modelValue }}

     <div>
        <button @click="update">修改</button>
     </div>
 </div>
</div>
</template>
<script setup lang='ts'> 

 import {ref,reactive,defineProps,defineEmits} from 'vue';

 const emit = defineEmits(["update:modelValue"]);

 const props = defineProps(["modelValue"]);

 const update = ()=>{
     
    emit("update:modelValue","北京欢迎您");
 }

</script>
<style scoped lang='less'>
.box{
    background: skyblue;
    width: 100%;
    height: 100px;
}
</style>